|Exfiltration in Sewer Systems (EPA/600/R-01/034) December 2000
Project Summary (8 pp, 120 KB)
This study focused nationally on the quantification of leakage of sanitary and industrial sewage from sanitary sewer pipes. The method for estimating exfiltration amounts used ground water table information to identify areas of the country where the hydraulic gradients of the sewage were typically positive, i.e., the sewage flow surface within pipelines was above the ground water table.
An examination of national ground water table elevations reveals that the contiguous United States is composed of ground water regions (established by the U.S. Geological Survey) that are markedly different. Much of the northeastern, southeastern, and midwestern United States has relatively high ground water tables that are higher than the sewage flow surface, resulting in inflow or infiltration. Conversely, a combination of relatively low ground water tables and shallow sewers creates the potential for widespread exfiltration in communities located in the western United States.
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